The present invention relates to ultrasonic bone testing and more particularly to an improved apparatus for coupling ultrasonic energy into and out of a patient's foot without requiring immersion of the patient's foot in a liquid.
It has previously been proposed to screen for osteoporosis and other degenerative bone diseases by transmitting ultrasonic energy of differing frequencies through the calcaneus in a patient's foot and by measuring the selective attenuation of energy by the bone. One particular apparatus for conducting such testing is disclosed in U.S. Letters Pat. No. 4,774,959 issued Oct. 4, 1988 to Stuart B. Palmer and Christian M. Langton and entitled Narrow Band Ultrasonic Frequency Attenuation Bone Measurement System. In the apparatus disclosed in that patent, a patient's foot is immersed in a liquid containing tank and the calcaneus is located between a pair of opposing transducers. As is understood by those skilled in the art, immersion in a liquid, particularly with a wetting agent included, is an effective way of coupling ultrasonic energy into and out of an irregularly shaped and surfaced object such as a human foot. For use as a general screening technique, however, the use of an immersing procedure is relatively time consuming and messy. On the other hand, the presence of air or other gas in between an ultrasonic transducer and an object to be tested will interfere with the coupling of ultrasonic energy and will lead to inconsistent measurements.
Among the several objects of the present invention may be noted the provision of ultrasonic bone testing apparatus which permits ultrasonic energy to be efficiently coupled into and out of an appropriate portion of a patient's body; the provision of such apparatus which facilitates the coupling of ultrasonic energy without requiring immersion; the provision of such apparatus which is useful for mass screening; the provision of such apparatus which is easy to operate; the provision of such apparatus which is relatively tolerant of patient positioning; the provision of such apparatus which permits testing to be conducted quickly; the provision of such apparatus which promotes reproducible measurements; the provision of such apparatus which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.